Many pumps include a static seal that is in contact with a rotating seal. These two seals co-act to minimize leakage out of the housing of the pump. However, since there is a frictional interface of the rotating seal sliding on the static seal, these seals can also coact to create heat from sliding friction. This heat can provide several deleterious effects including increased seal wear and also formation of vapor bubbles.
To overcome these adverse affects, some pumps incorporate secondary cooling passages that provide a cooling medium to the seal interface to reduce the temperature. For example, in a centrifugal pump, the cooling passage may connect the high pressure fluid exiting the pump with a region of lower pressure near the inner diameter of the pump.
However, some pumps include fluid passageways of simple shape which do not provide optimum protection for the pump seals. Further, some newer pumps are required to work in hotter applications where the removal of heat from the frictional seal interface is critical. Sometimes the simply shaped fluid passageways provide inadequate cooling flow such that reasonable operating temperatures cannot be achieved. In yet other applications the pressure of the cooling fluid in the vicinity of the seal is too low to prevent the formation of vapor bubbles and damage by cavitation. In yet other applications, the fluid passageway is directed toward the centerline of the rotor, such that there is no tangentially-directed fluid to flush debris away from the seal interface.
The present invention provides solutions to these problems in novel and unobvious ways.